1. Field of the Invention
The present invention relates to an absorption refrigerating machine, used as an outdoor equipment of an absorption air conditioner, for cooling a heating medium for use in a cooling operation of an indoor air conditioner body.
2. Description of the Related Art
An absorption refrigerating machine has been heretofore known as the one applied to an absorption air conditioner disclosed in Japanese Patent Application Laid-open No. 10-26437, for example. In this absorption refrigerating machine, water is used as refrigerant and lithium bromide is used as absorbent. As shown in FIG. 3, this machine comprises: a high-temperature regenerator 110 having a fin-tube heat exchanger 112 for heating, by a heat of combustion of a burner 111, a lithium bromide aqueous solution (hereinafter simply referred to as a low-concentration solution, an intermediate-concentration solution and a high-concentration solution in accordance with the concentration of the lithium bromide) that is a low-concentration absorbing solution supplied from a solution pump 150; a high-temperature regenerator vapor-liquid separator 113 (hereinafter simply referred to as a high-temperature separator) for separating the low-concentration solution heated by the high-temperature regenerator 110 into a water vapor and the intermediate-concentration solution; a low-temperature regenerator 120 for heating the intermediate-concentration solution fed to a fin-tube heat exchanger 121 by the water vapor resulting from the separation performed by the high-temperature separator 113; a low-temperature regenerator vapor-liquid separator 122 (hereinafter simply referred to as a low-temperature separator) for separating the heated intermediate-concentration solution into the water vapor and the high-concentration solution; a condenser 130 for cooling and liquefying the water vapor from the low-temperature separator 122; an evaporator 141 for evaporating the water condensed by the condenser 130 and the low-temperature regenerator 120; and an absorber 142 for absorbing the water vapor from the evaporator 141 by the high-concentration solution.
The evaporator 141 and the absorber 142 are integrated into an evaporating/absorbing chamber 143. The chamber 143 is formed between a cold water pipe 160 and an outer pipe 140. The cold water pipe 160 has a double-pipe structure comprising the outer pipe 140 disposed coaxially outside the cold water pipe 160 extending from an indoor cooling machine (not shown). A solution circuit K from the absorber 142 to the high-temperature regenerator 110 includes the above-described solution pump 150 for circulating and supplying the low-concentration solution to the high-temperature regenerator 110; a low-temperature heat exchanger 151 for heat-exchanging the high-concentration solution fed from the low-temperature separator 122; and a high-temperature heat exchanger 152 for heat-exchanging the intermediate-concentration solution fed from the high-temperature separator 113. Also, the solution circuit from the high-temperature heat exchanger 152 to the low-temperature regenerator 120 includes a pressure reducing valve 114.
Next, the cooling operation of this absorption air conditioner will be described. The solution pump 150 starts operating. By the ignition of the burner 111, the low-concentration solution flowing through the fin-tube heat exchanger of the high-temperature regenerator 110 is heated, and thus the water vapor is generated. The heated low-concentration solution is then separated into the water vapor and the intermediate-concentration solution by the high-temperature separator 113. The intermediate-concentration solution is reduced in temperature by the high-temperature heat exchanger 152. Then, the intermediate-concentration solution is supplied to the low-temperature regenerator 120. When the intermediate-concentration solution flows through the fin-tube heat exchanger, it is reheated by the water vapor from the high-temperature separator 113. The intermediate-concentration solution is separated into the water vapor and the high-concentration solution by the low-temperature separator 122. The high-concentration solution is reduced in temperature by the low-temperature heat exchanger 151. Then, the high-concentration solution is dropped to an inner surface of the outer pipe 140. Meanwhile, the water vapor is cooled and condensed by the condenser 130. The water vapor is then dropped to an outer surface of the cold water pipe 160 of the evaporating/absorbing chamber 143. The dropped water is evaporated due to a low pressure in the evaporating/absorbing chamber 143. The heat equivalent to vaporizing heat is removed from the water flowing through the cold water pipe 160, and thus the water is cooled. Thereby, the cold water circulating through the cold water pipe 160 is led to an indoor equipment. Thus, the cooling operation is performed. The high-concentration solution absorbs the evaporated water vapor, so that it is changed into the low-concentration solution. The low-concentration solution passes through the low-temperature heat exchanger 151 and the high-temperature heat exchanger 152 by the solution pump 150, and thus its temperature is raised. Then, the low-concentration solution is fed to the high-temperature regenerator 110.
In the above-mentioned absorption refrigerating machine, after the stop of the operation, the high-concentration solution remains from the low-temperature separator 122 to a distal end of the absorber 142, more particularly. Thus, the lithium bromide is crystallized due to the drop in an outdoor air temperature or a solution temperature. As a result, the inside of the machine may be clogged with the crystallized lithium bromide. The prevention of such crystallization of the lithium bromide requires a dilution operation for circulating the low-concentration solution through a flow path which the lithium bromide aqueous solution flows through. The circulation of the low-concentration solution needs a pressure difference within the path. Desirably, the dilution operation is thus performed just after the stop of the operation. However, the dilution operation just after the operation causes a problem. That is, when the operation is restarted, it takes a long time to recover a steady operation condition where, within the path, the solution is located in accordance with a predetermined concentration profile and a predetermined pressure difference is made.
On the other hand, the low-concentration solution can be circulated by its own weight so as to perform the dilution operation. However, in this case, the absorption refrigerating machine is made higher so as to thereby overcome a pressure loss caused due to a restriction or the like in the path. Otherwise, the lithium bromide aqueous solution flows into a gas passage. Consequently, the refrigerating machine could not function. It is thus necessary to increase the size of the whole refrigerating machine by making the refrigerating machine higher. However, the trouble in installation is caused due to the increase in a space in which the refrigerating machine is installed. Also, the price goes up due to the increase in the size of the refrigerating machine.
The present invention is intended to solve the above problems. An object of the present invention is to provide an absorption refrigerating machine which can carry out the operation for diluting an absorbing solution after the stop of the operation when necessary and can smoothly restart the operation and which does not involve increasing the size of an apparatus.